And pressed it into the piston. The bury was .125, and the stick out was .030", which is the depth of the horizontal leg of the L shaped ring, flush with the inside of the upright leg. The upper part of the piston is relieved above (to the left in the photo) the ring groove to accommodate the outer ...

Drilling the piston for the ring locating pin .0625" , 300 degrees from the front of the piston. This will allow it to line up with one of the lands between uniflow ports: https://www.sredmond.com/srhacksaw/FlashEngine1x75/Piston11.jpg And turning a locating pin using a stainless steel cap screw as ...

Testing the ring's fit in the cylinder:


The gap just closes.

A dyke ring, split, expanded and heat heat treated:




Testing in the piston groove before compressing. The piston is still attached by the crown to the chucking piece:

Thank you Fred, and RNoe. Just catching up here. Parting a ring off after sizing the blank, and using a form tool to form the dyke ring "L" shape: https://www.sredmond.com/srhacksaw/FlashEngine1x75/Ring1.jpg Splitting the ring using a Morse taper dead center as a wedge: https://www.sredmond.com/srha...

Piston lapping: Lap made: https://www.sredmond.com/srhacksaw/FlashEngine1x75/PistonLap5.jpg Lapping the piston: https://www.sredmond.com/srhacksaw/FlashEngine1x75/Piston7.jpg Measuring, the piston was lapped to 0.996" for a 3 thou clearance. https://www.sredmond.com/srhacksaw/FlashEngine1x75/Piston8...

Cylinder lapping Lap made: https://www.sredmond.com/srhacksaw/FlashEngine1x75/Lap2.jpg Compound: https://www.sredmond.com/srhacksaw/FlashEngine1x75/Lap3.jpg Lapping: https://www.sredmond.com/srhacksaw/FlashEngine1x75/Lap4.jpg Finish was cross hatched, but too fine to see. Cylinder finished out to 0....

Thanks Fred, very good points, and I have been giving a lot of thought to that. The ring will definitely be pinned with a stainless steel pin to keep the gap away from the ports. I've thought about easing edges, but not totally convinced that's going to be a positive. The engine follows very closely...

Cylinder ported and lapped:



Piston cast, turned, bored, cutting ring groove:

Hi Dieter,

Two small spots of superglue on the flange. After drilling I knocked them apart. Superglue has poor shock resistance if the glue area is small.

Here is the bearing housing and crankcase together: